A vacuum cooking pot of the prior art can be used as a regular pot by exhausting the air through the check valve (or the vacuum release valve) due to the internal expansion of the cooking chamber during boiling.
When it is cooled down after boiling, the inflow of the external air through the check valve (or the vacuum release valve) is blocked due to the internal contraction of the cooking chamber, and performs so called pumping-like function that pulls the lid to downwards direction and creates a vacuum inside such that the lid is stuck to the container thereby preventing separation thereof.
When the contents is stored as it is under a vacuum, spoiling of the food can be prevented as long as the vacuum is maintained thereby solving the inconvenience of continuous boiling thereof.
The vacuum can be released by re-boiling or holding and pushing up the check valve (or the vacuum release valve) (refer to patent literature 1 and 2).
However, the check valve (or the vacuum release valve) of the prior art is made separately from the lid handle, and the handle is holdably formed in the center of the lid therefore the lid cannot be erected.
Meanwhile, as a check valve of the prior art, for example, the one described in the patent literature 3 is disclosed.
As illustrated in FIG. 11, a check valve 120 which is inserted into a mounting hole 116 formed at the bottom surface of the circular pit 118 of the lid body 110, is made of a silicon material and mainly comprised of a body 122, a first flange 125, and a second flange 126.
First, a pressure-relief path 123 is formed inside of the body 122; and a release hole 124 releasing pressure in conjunction with the pressure-relief space 123 is formed in the circumference of the body. Then, a first flange is formed at the lower circumference of the release hole 124 of the body 122 such that the tight contact with the inner surface prevents an arbitrary separation of the body 122 from the mounting hole 116. Finally, a second flange 126 is formed at the upper circumference of the release hole 124 of the body 122 such that the tight contact with the outer surface of the mounting hole 116 and the through-hole 117 prevents downward slipping of the body 122.
However, when the overflow exceeds the release hole 124, the overflow cannot be prevented by the second flange 126 only.